In general, the design of floor drains has not drastically changed over the years. Floor drains are typically installed into basements, subfloors or weeping tiles of buildings to allow any water flowing into the same to flow into a sewer line. Most conventional floor drains contain what is known as a “p-style” trap. A serious problem with these conventional floor drains is that while the p-style trap allows water to drain from the basement, subfloor or weeping tile, the p-style trap can allow sewer water from the sewer line to back up into the building due to rising water levels from various causes, including overflow from excess water, or due to debris clogging the sewer line. This type of trap generally allows for some water to remain in the adjacent drain pipe, but if the water in a conventional floor drain system containing a p-style trap completely evaporates or drains, sewer gases from the sewer system can escape into the building through the floor drain, which can be very harmful to occupants of the building.
Various solutions have been suggested for attempting to overcome these problems of conventional floor drain systems.
For example, Canadian Patent 2,429,950 (U.S. Pat. No. 6,795,987) discloses a floor drain system in which the device is intended to stop the backflow of water and of sewer gases, by providing a valve having a flexible outlet, which is intended to open from a curled closed position to an uncurled open position in response to water entering from the inlet above. However, the valve outlet is located within a single compartment, such that in the event that a large volume of liquid backed up into the single compartment from the external sewer system when the valve was already in the uncurled open position within the liquid, the flexible outlet would be impeded by the high pressure of the water from returning to a curled closed position, to prevent liquid flow upwards through the drain. Further, any solid matter can readily become lodged in the flexible outlet and impede it from curling to return to its intended closed position.
Canadian Patent 1,196,543 (U.S. Pat. No. 4,487,219) discloses a floor drain device which is intended to prevent fluid backing up into a building, by providing a cupped sealing device intended to prevent sewer liquids and associated bacteria from passing through the drain into the building. The device attempts to prevent the height of liquid in its single compartment from exceeding the height of the upper level of the outlet pipe, so as to provide an air gap between the liquid in the compartment and the narrowed inlet aperture from the upper opening of the unit. However, in the event of a substantial, particularly if sudden, backflow into the unit through the outlet from the sewer system, the air gap could be eliminated so that liquid could flow upwards into the building; or could force the unit itself upwards through the drain opening. Further, if the unit goes dry, the device has no means of preventing gases passing up through the drain into the building.
Canadian Patent 1,272,659 (U.S. Pat. No. 4,744,109) discloses a device which is intended to prevent radon gas leakage into a building, but does not include any means of preventing the backflow of water through the floor drain and into the building.
It has been found that an improved trap can be provided for a floor drain system which prevents the backflow of sewer water and sewer gases from the sewer line into the building, thereby avoiding the problems of excess water entering through the drain into the basement, and the consequent costs of repairs for damage from the backflow of water through the sewer line, and the environmental risks, including injury from gas or bacteria, and discomfort from consequent odors, to occupants of the building.